On Sat, 4 Sep 2004, Laurent Pinchart wrote: > > Maybe we're talking about different traces. I'm referring to the trace > > for the Zoom modem (a low-speed device according to Steve), as attached to > > Yes we are. The Zoom modem is a USB 1.0 device according to Steve, but he > didn't mention if it is a low-speed or high-speed device (well if he did I > didn't notice). > > Steve sent me another trace which he didn't post to the list due to its size. > You can find the zipped file at http://ben.lautard.free.fr/mouse_enum.txt.gz > (I asked a friend to host it for me, so please download it as soon as you > can, it will probably not stay there for very long).
Okay, I got it. Thanks. > The trace shows the enumeration of a USB 1.1 low-speed HID device. It shows > (not very clearly, as its very verbose, but still) that Windows XP enumerates > the low-speed device with a 18 bytes Get-Device-Descriptor request. Hmm... It's a little tricky to decipher this, as you say. At the start is a bunch of Events labelled "Keep_Alive". Just after Event 32 there's something labelled "Transfer Header" -- I suppose it is the decode of the message that follows. Next I see a Transaction Header for Transaction Number 0; this must be the start of the first Get-Device-Descriptor control message. It shows a Setup packet, then a DATA0 packet, then an ACK. In the DATA0 packet the 7th byte is 0x40; hence the request is for 64 bytes. The device transfers all 18 bytes in three transactions, appropriate for a low-speed device with maxpacket = 8. Finally, Event 35 is a bus reset. Alan Stern ------------------------------------------------------- This SF.Net email is sponsored by BEA Weblogic Workshop FREE Java Enterprise J2EE developer tools! Get your free copy of BEA WebLogic Workshop 8.1 today. http://ads.osdn.com/?ad_id=5047&alloc_id=10808&op=click _______________________________________________ [EMAIL PROTECTED] To unsubscribe, use the last form field at: https://lists.sourceforge.net/lists/listinfo/linux-usb-devel
